Heat exchanger and duplex type heat exchanger

ABSTRACT

A heat exchanger has first and second header tanks, multiple built-up tubes connected between the header tanks. A communication pipe is also connected between the header tanks. A separator is provided in the first header tank, so that a tank space of the first header tank is divided into first and second sub-tank spaces. The first sub-tank space is communicated with the multiple built-up tubes, whereas the second sub-tank space is communicated with the communication pipe. An inlet pipe is connected to the second sub-tank space and fluidically connected to an automatic transmission through a vehicle delivery pipe, wherein a flow path sectional area of the communication pipe is almost equal to that of the delivery pipe.

CROSS REFERENCE TO RELATED APPLICATION

This application is based on Japanese Patent Application No. 2005-268861 filed on Sep. 15, 2005, the disclosure of which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a heat exchanger suitable for use as an oil-cooler for cooling automotive engine oil, working fluid for an automatic transmission (hereinafter referred to as ATF (Automatic Transmission Fluid)) or the like. The present invention further relates to a duplex type heat exchanger, in which another heat exchanger such as a condenser for an air conditioning apparatus is integrally provided to the first mentioned heat exchanger.

BACKGROUND OF THE INVENTION

A heat exchanger of this kind is well known in the art, for example, as disclosed in Japanese Patent Publication No. 2004-293878. The heat exchanger of this kind is widely used as a radiator, an oil cooler, a condenser and the like. In the heat exchanger, a core portion is formed by multiple built-up tubes and fins interposed between the tubes. Both ends of the tubes are connected to a pair of tank portions, so that the tubes are fluidically communicated with the tank portions.

In the heat exchanger, internal fluid (engine cooling water, oil, refrigerant, and so on) flows from one of the tank portions to the other tank portion after the internal fluid has passed through the multiple tubes. Cooling air is supplied to an outer side of the core portion, so that the cooling air passes through the core portion. The internal fluid is cooled by heat exchange between the internal fluid and the cooling air. Cooling performance of the heat exchanger can be changed (increased or decreased) by changing length of the tubes, number of built-up tubes, specifications of the fins, and so on.

In the case that capacity for the cooling performance is required to be made smaller without changing the length of the tubes, the number of tubes is generally reduced. However, when the number of the tubes is reduced, total flow path area for working fluid is correspondingly reduced, and fluid flow resistance in the core portion is instead increased. Then, high cooling performance can not be expected. On the other hand, if the number of the tubes was not reduced in order not to increase the fluid flow resistance, the capacity for the cooling performance can not be decreased, and over-cooling for the working fluid may happen.

SUMMARY OF THE INVENTION

The present invention is made in view of the foregoing problems, and has an object to provide a heat exchanger and/or a duplex type heat exchanger in which the cooling performance can be appropriately maintained but the flow resistance for working fluid can be reduced.

According to one of features of the present invention, a heat exchanger has a pair of first and second header tanks, and an inlet pipe and an outlet pipe provided to one of the header tanks, wherein the inlet and outlet pipes are connected to a heat generating device through delivery pipes so that working fluid is supplied from the heat generating device to the header tank to which the inlet and outlet pipes are provided and the working fluid returns to the heat generating device from the same header tank.

The heat exchanger further has a first group of multiple built-up tubes, both longitudinal ends of which are respectively connected to the header tanks, so that the working fluid flows from one of the header tanks to the other header tank through the multiple built-up tubes. A communication pipe is connected between the header tanks so that tank spaces formed in the respective header tanks are fluidically communicated with each other through the communication pipe. The communication pipe is arranged at an outer side of the built-up tubes in a direction of building-up the tubes, and the communication pipe has a flow path sectional area almost equal to that of the delivery pipes.

In the above heat exchanger, a separator is provided in the header tank to which the inlet and outlet pipes are provided, for dividing the tank space formed by the header tank into first and second sub-tank spaces, so that the first sub-tank space is communicated with the tubes and the second sub-tank space is communicated with the communication pipe. A bypass flow path having a certain flow resistance is formed in the separator for communicating the first and second sub-tank spaces with each other.

Furthermore, in the above heat exchanger, the inlet pipe is fluidically connected to one of the sub-tank spaces, whereas the outlet pipe is fluidically connected to the other sub-tank space, so that a certain amount of the working fluid directly flows from the sub-tank space connected with the inlet pipe to the other sub-tank space connected with the outlet pipe through the bypass flow path, and the remaining amount of the working fluid flows from the sub-tank space connected with the inlet pipe to the other sub-tank space connected with the outlet pipe through the communication pipe and the multiple tubes.

According to another feature of the present invention, a heat exchanger has a pair of first and second header tanks, an inlet pipe provided to the second header tank, and an outlet pipe provided to the first header tanks, wherein the inlet and outlet pipes are connected to a heat generating device through delivery pipes so that working fluid is supplied from the heat generating device to the second header tank and the working fluid returns to the heat generating device from the first header tank.

In the heat exchanger, a first group of multiple built-up tubes is provided, both longitudinal ends of which are respectively connected to the header tanks, so that the working fluid flows from the second header tank to the first header tank through the multiple built-up tubes. A communication pipe is further connected between the header tanks so that tank spaces formed in the respective header tanks are fluidically communicated with each other through the communication pipe. The communication pipe is arranged at an outer side of the built-up tubes in a direction of building-up the tubes, and the communication pipe has a flow path sectional area almost equal to that of the delivery pipes.

Furthermore, a separator is provided in the first header tank, for dividing the tank space formed by the first header tank into first and second sub-tank spaces, so that the first sub-tank space is communicated with the tubes and the second sub-tank space is communicated with the communication pipe. A bypass flow path having a certain flow resistance is formed in the separator for communicating the first and second sub-tank spaces with each other.

In the above heat exchanger, a certain amount of the working fluid flows from the tank space formed by the second header tank to the second sub-tank space of the first header tank through the communication pipe, whereas the remaining amount of the working fluid flows from the tank space formed by the second header tank to the first sub-tank space of the first header tank through the multiple tubes. Then, the working fluid flows from the second sub-tank space to the first sub-tank space though the bypass flow path and flows out of the first sub-tank space through the outlet pipe.

According to a further feature of the present invention, a heat exchanger has a pair of first and second header tanks, an inlet pipe provided to the second header tank, and an outlet pipe provided to the first header tanks, wherein the inlet and outlet pipes are connected to a heat generating device through delivery pipes so that working fluid is supplied from the heat generating device to the second header tank and the working fluid returns to the heat generating device from the first header tank.

In the heat exchanger, a first group of multiple built-up tubes is provided, such that both longitudinal ends thereof are respectively connected to the header tanks in order that the working fluid flows from the second header tank to the first header tank through the multiple built-up tubes. A communication pipe is further connected between the header tanks so that tank spaces formed in the respective header tanks are fluidically communicated with each other through the communication pipe, wherein the communication pipe is arranged at an outer side of the built-up tubes in a direction of building-up the tubes, and the communication pipe has a flow path sectional area almost equal to that of the delivery pipes.

Furthermore, a separator is provided in the second header tank, for dividing the tank space formed by the second header tank into first and second sub-tank spaces, so that the first sub-tank space is communicated with the tubes and the second sub-tank space is communicated with the communication pipe. A bypass flow path having a certain flow resistance is formed in the separator for communicating the first and second sub-tank spaces with each other.

Accordingly, in the above heat exchanger, the inlet pipe is fluidically connected to the first sub-tank space, and a certain amount of the working fluid directly flows from the first sub-tank space to the second sub-tank space through the bypass flow path, and then to the tank space formed by the first header tank through the communication pipe. The remaining amount of the working fluid flows from the first sub-tank space to the tank space formed by the first header tank through the multiple tubes.

According to a still further feature of the present invention, a duplex type heat exchanger for a vehicle has first and second heat exchangers.

The first heat exchanger has first and second header tanks, and first multiple tubes, both longitudinal ends of which are connected to the first and second header tanks, so that tank spaces formed in the first and second header tanks are fluidically communicated with each other through the first multiple tubes. The second heat exchanger has third and fourth header tanks, and second multiple tubes, both longitudinal ends of the first multiple tubes are connected to the third and fourth header tanks, so that tank spaces formed in the third and fourth header tanks are fluidically communicated with each other through the second multiple tubes, wherein the third header tank is integrally formed with the first header tank and the fourth header tank is integrally formed with the second header tank.

The heat exchanger further has a communication pipe connected to the first and second header tanks, so that the tank spaces formed in the first and second header tanks are fluidically communicated with each other through the communication pipe. A separator is provided in the first header tank for separating the tank space formed in the first header tank into first and second sub-tank spaces, so that each one end of the first multiple tubes is communicated with the first sub-tank space and one end of the communication pipe is communicated with the second sub-tank space.

An inlet pipe is provided to the first header tank to be fluidically communicated to the second sub-tank space, and the inlet pipe is further connected to an automotive parts device through a vehicle delivery pipe. An outlet pipe is provided to the first header tank to be fluidically communicated to the first sub-tank space, and the outlet pipe is further connected to the automotive parts device through the vehicle delivery pipe.

A bypass flow path is formed in the separator, so that a portion of working fluid from the inlet pipe flows from the second sub-tank space to the tank space of the second header tank, whereas the remaining portion of the working fluid flows from the second sub-tank space to the first sub-tank space through the bypass flow path, wherein a flow path sectional area of the communication pipe is almost equal to that of the vehicle delivery pipe.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawing. In the drawing:

FIG. 1 is a front view showing a duplex type heat exchanger according to a first embodiment of the present invention;

FIG. 2 is a schematic cross sectional view of a header tank in which a separator is provided, when viewed in a direction indicated by an arrow II in FIG. 1;

FIG. 3 is a front view showing a duplex type heat exchanger according to a second embodiment;

FIG. 4 is a front view showing a duplex type heat exchanger according to a third embodiment;

FIG. 5 is a front view showing a duplex type heat exchanger according to a fourth embodiment; and

FIG. 6 is a front view showing a duplex type heat exchanger according to a fifth embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(First Embodiment)

A first embodiment of the present invention relates to a duplex type heat exchanger 10, in which a heat exchanger 200 is integrally provided to another heat exchanger 100. The heat exchanger 200 is an oil-cooler for cooling automatic transmission fluid (ATF) for anautomotivetransmissiondevice, whereas the other heat exchanger 100 is a condenser for cooling and condensing refrigerant in a refrigerating cycle for an automotive air conditioning apparatus. A structure of the duplex type heat exchanger 10 will be explained with reference to FIGS. 1 and 2, wherein FIG. 1 is a front view showing the entire portion of the heat exchanger, and FIG. 2 is a schematic cross sectional view showing a header tank in which a separator 250 is provided, when viewed in a direction indicated by an arrow II in FIG. 1.

The heat exchanger (the oil-cooler) 200 is referred to as a first heat exchanger, the heat exchanger (the condenser) 100 is referred to as a second heat exchanger. The automatic transmission device is also referred to as a heat generating device or an automotive parts device.

A refrigerating cycle is composed of a closed circuit, in which a compressor, the condenser 100, an expansion valve, an evaporator and soon are connected by a refrigerant pipe arrangement. The condenser 100 is generally mounted in an engine compartment by brackets 270 at such a position, at which the condenser 100 receives more cooling air (vehicle traveling wind). The condenser 100 is generally located at a forward side of the radiator for cooling engine cooling water. The brackets 270 are fixed to header tanks 120, 220, 230 and a modulator 140. The vehicle traveling wind as well as the cooling air are supplied to core portions 110, 210 by an air blowing fan (not shown), in a direction perpendicular to the drawing (FIG. 1) from a front side to a back side.

The condenser 100 is composed of the core portion 110, the header tank 120 of the right hand side, the header tank 130 of the left hand side, the modulator 140, and soon. Each element described below is made of aluminum or aluminum base alloy. Those elements are assembled together by intrusion, caulking, fitting by jigs and so on, and those elements are soldered together by soldering material clad on respective surfaces of the elements.

In the core portion 110, multiple tubes 111 and fins 112 are alternately built-up, wherein refrigerant flows through the inside of the tubes 111. The fins 112 are provided to increase a heat-exchanging efficiency by enlarging heat radiating surfaces. A side plate 113 is provided at an lower outer side of a lowermost fin 112 as a reinforcing member.

The tube 111 is formed into a flat shape in its cross section perpendicular to a longitudinal direction of the tube. An inside passage of the tube 111 is divided into multiple compartments by multiple partitioning walls. The tube 111 is made by, for example, an extrusion. The fin 112 is a corrugated fin made from a band plate of thin thickness and formed into a wave shape by a rolling process. The side plate 113 is formed into a U shape in its cross section, and an open side of the side plate 113 is directed to a direction opposite to the tubes 111. Both longitudinal ends of the side plate 113 are formed as a flat plate portion which will be soldered to the header tanks 120, 130, as described below. Hereinafter, a built-up direction of the tubes 111 is referred to as a vertical direction, whereas the longitudinal direction of the tubes 111 is referred to as a horizontal direction.

The core portion 110 is divided into a condensing portion 110A at an upper side and a super cooling portion 110B at a lower side. The condensing portion 110A has a first tube portion 111A having a predetermined number of built-up tubes 111, and the super cooling portion 110B has a second tube portion 111B having the remaining number of built-up tubes 111, wherein the number of the built-up tubes of the second tube portion 111B (at the super cooling portion 110B) is set to be smaller than that of the built-up tubes of the first tube portion 111A (at the condensing portion 110A).

A pair of header tanks 120 and 130 are provided at right and left hand sides of the core portion 110 (i.e., at both longitudinal ends of the tubes 111), wherein the header tanks 120 and 130 extend in the vertical direction. Each of the header tanks 120 and 130 is formed into such a shape similar to a cylindrical shape having a circular cross section. Each of the header tanks 120 and 130 is composed of a header plate and a tank plate, wherein the header plate and tank plate have a semi-circular shape in its cross section and fixed to each other.

Multiple tube holes (not shown) are formed in the header tanks 120 and 130. Both longitudinal ends of the respective tubes 111 are fitted into the tube holes, so that both of the header tanks 120 and 130 are fluidically communicated with each other through the multiple tubes 111. Both longitudinal ends of the side plate 113 are likewise fitted into plate holes (not shown) formed in the header tanks 120 and 130, so that the side plate 113 is firmly fixed to the header tanks 120 and 130.

Opening ends 121 and 131 are formed at both vertical ends of the respective header tanks 120 and 130, and closed by header caps 150.

Multiple separators 122, 123, 124, 132, 133, and 134 are provided in the insides of the header tanks 120 and 130, in order to separate the inside spaces into multiple independent sub-tank spaces, more exactly, three independent sub-tank spaces 120 a, 120 b, 120 c, and 130 a, 130 b, 130 c in each of the header tanks 120 and 130.

The separators 122 and 132 are provided in the respective header tanks 120 and 130 at middle positions of the respective header tanks away from the respective header caps 150, to divide the inside spaces of header tanks 120 and 130 into the tank spaces for the condenser 100 and the tank spaces for the oil-cooler 200. The separators 123 and 133 are provided in the tank spaces for the condenser 100 at such positions which correspond to a boundary between the condensing portion 110A and the super cooling portion 110B. The separator 124 is provided in the tank space (right hand side) for the condenser 100 between the separators 122 and 123, whereas the separator 134 is provided in the tank space (left hand side) for the condenser 100 between the separators 132 and 133. The separator 124 is provided in the header tank 120 at such a position which is higher in the vertical direction than a position of the separator 134 provided in the header tank 130.

An inlet joint 161 is provided to the header tank 120 (right hand side) between the separators 122 and 124, so that the inlet joint 161 is fluidically communicated to the sub-tank space 120 c formed between the separators 122 and 124. An outlet joint 162 is provided to the header tank 120 (right hand side) between the separator 123 and the header cap 150, so that the outlet joint 162 is fluidically communicated to the sub-tank space 120 a formed between the separator 123 and the header cap 150.

The modulator 140 is provided to the header tank 130 at the opposite site to the tubes 111A and 111B. The modulator 140 is a receiver for separating the refrigerant from the condensing portion 110A into liquid-phase and gas-phase refrigerant, and for supplying the liquid-phase refrigerant to the super cooling portion 110B. The modulator 140 is composed of a cylindrical container, a cap 141 and a screw cap 142, wherein the cap 141 and the screw cap 142 are respectively fixed to longitudinal ends of the cylindrical container. An inside space of the modulator 140 is fluidically connected to the middle sub-tank space 130 b and the lower sub-tank space 130 a of the header tank 130 in the left hand side. A desiccant 143 and a filter 144 are disposed in the inside of the modulator 140 for removing the water contained in the refrigerant and extraneous material broken into the refrigerating cycle.

The header tanks 120 and 130 are respectively referred to as third and fourth header tanks. The tubes 111 are referred to as a second group of tubes or second multiple tubes.

The oil-cooler 200 is formed at the upper side of the condenser 100, and composed of a core portion 210, a header tank 220 of the right hand side, a header tank 230 of the left hand side, and so on. Each element forming the oil-cooler 200 is likewise made of aluminum or aluminum base alloy, those elements are assembled together by intrusion, caulking, fitting by jigs and so on, and those elements are soldered together to the condenser 100 by soldering material clad on respective surfaces of the elements.

In the core portion 210, multiple tubes 211 and fins 212 are alternately built-up, wherein the working fluid (ATF) flows through the inside of the tubes 211. The fins 212 are provided to increase a heat-exchanging efficiency by enlarging heat radiating surfaces. A side plate 213 is provided at an upper outer side of an uppermost fin 212 as a reinforcing member.

In the embodiment, the tubes 211, the fins 212 and the side plate 213 for the oil-cooler 200 have the same specifications to the tubes 111, the fins 112 and the side plate 113 for the condenser 100. A direction of built-up tubes 211 is the same to the direction of built-up tubes 111. Namely, the tubes 211 are continuously built-up on the tubes 111.

A dummy tube 311 is arranged between the core portion 110 and the core portion 210, namely between the tube 111 and the tube 211. The dummy tube 311 has also the same specifications to the tube 111. The dummy tube 311 is arranged at a position vertically higher than the positions of the separators 122 and 132 provided in the header tanks 120 and 130 of the condenser 100.

Each of the header tanks 120 and 130 is vertically elongated in the upper direction to respectively form the pair of header tanks 220 and 230. Each of separators 221 and 231 is provided in the header tanks 220 and 230 at such position between the dummy tube 311 and the lowermost tube 211. Sub-tank spaces 220 a, 220 b, and 230 c for the header tanks 220 and 230 are respectively formed between the separator 221 and the header cap 150, and between the separator 231 and the header cap 150.

Multiple tube holes (not shown) are formed in the header tanks 220 and 230. Both longitudinal ends of the respective tubes 211 are fitted into the tube holes, so that both of the header tanks 220 and 230 are fluidically communicated with each other through the multiple tubes 211. Both longitudinal ends of the side plate 213 are likewise fitted into plate holes (not shown) formed in the header tanks 220 and 230, so that the side plate 213 is firmly fixed to the header tanks 220 and 230.

Sub-tank spaces 120 d and 130 d, which are respectively formed between the separators 122 and 221, and between the separators 132 and 231, are such spaces into which any of the refrigerant and ATF does not flow. Accordingly, none of the refrigerant and the ATF flows through the dummy tube 311. Therefore, the sub-tank spaces 120 d and 130 d as well as the dummy tube 311 are filled with air.

A communication pipe 240 is arranged above the core portion 210 along an inside groove formed by a U-shaped (in its cross section) side plate 213. Both longitudinal ends of the pipe 240 is fluidically connected to the header tanks 220 and 230. The pipe 240 has a circular shape in its cross section, and has a fluid flow area similar to that of a delivery pipe for ATF (not shown) for the vehicle. The pipe 240 has a curved portion 241 at its middle portion, which is bent in the upper direction.

A separator 250 is provided in the header tank 220 (of the right hand side) at such a position between the pipe 240 and the uppermost tube 211 to form the sub-tank spaces 220 a and 220 b. An aperture (a bypass flowpath) 251 is formed at a center of the separator 250, as shown in FIG. 2, so that a certain amount of the working fluid (ATF) may flow from the sub-tank space 220 b to the sub-tank space 220 a. The aperture 251 has a certain flow resistance when the working fluid (ATF) flows therethrough.

An inlet pipe 261 is provided at the header tank 220 (of the right hand side) between the header cap 150 and the separator 250, so that the inlet pipe 261 is fluidically connected with the sub-tank space 220 b and the working fluid (ATF) flows into the sub-tank space 220 b from the inlet pipe 261. An outlet pipe 262 is also provided at the header tank 220 (of the right hand side) between the separator 250 and the separator 221, so that the outlet pipe 262 is fluidically connected with the sub-tank space 220 a and the working fluid (ATF) flows out from the sub-tank space 220 a to the outlet pipe 262.

The header tanks 220 and 230 are respectively referred to as first and second header tanks. The tubes 211 are referred to as a first group of tubes or first multiple tubes.

An operation of the duplex-type heat exchanger 10 will be explained.

The inlet joint 161 of the condenser 100 is connected to a discharge side of the compressor (not shown), whereas the outlet joint 162 is connected to the expansion valve (not shown). The refrigerant (e.g. 60° C.) discharged from the compressor flows from the inlet joint 161 into the sub-tank space 120 c of the header tank 120 on the right hand side. The refrigerant then flows through the first tube portion 111A in a pattern of a letter S, namely to the sub-tank space 130 c, the sub-tank space 120 b, and the sub-tank space 130 b,as indicated by a one-dot-chainline. The refrigerant is cooled down by the heat exchange with the cooling air when the refrigerant flows through the first tube portion 111A, and condensed and liquefied.

When the refrigerant flows into the sub-tank space 130 b of the header tank 130 on the left hand side, the refrigerant flows into the modulator 140. In the modulator 140, the refrigerant is separated into the gas-phase and liquid-phase refrigerant. Only the liquid-phase refrigerant flows out from the modulator 140 and flows into the sub-tank space 130 a, so that the liquid-phase refrigerant further flows through the second tube portion 111B. The refrigerant flowing through the second tube portion 111B is super-cooled by the cooling air, and flows into the sub-tank space 120 a. Then, the super-cooled refrigerant flows out through the outlet joint 162 to the expansion valve.

On the other hand, the inlet pipe 261 of the oil-cooler 200 is connected to a discharge side of an automatic transmission (not shown), whereas the outlet pipe 262 is connected to an inlet side of the automatic transmission through the vehicle delivery pipes (not shown). The working fluid (ATF) (e.g. 150° C.) for the automatic transmission discharged from the discharge side flows into the sub-tank space 220 b of the header tank 220 on the right hand side through the vehicle delivery pipe and the inlet pipe 261. A major portion of the working fluid (ATF) flows to the sub-tank space 230 c of the header tank 230 on the left hand side through the communication pipe 240, and then flows through the tubes 211 into the sub-tank space 220 a of the header tank 220 on the right hand side, in a flow patter of a letter U, as indicated by a dotted line. The working fluid then flows out through the outlet pipe 262 to the inlet side of the automatic transmission. The working fluid is cooled down when the working fluid flows through the tubes 211 by the cooling air. The flow resistance of the pipe 240 is almost equal to that of the vehicle delivery pipe.

A certain amount (e.g. 20%) of the working fluid (ATF) flowing into the sub-tank space 220 b of the header tank 220 directly flows into the sub-tank space 220 a through the aperture (the bypass flow path) 251. And such working fluid flows out from the sub-tank space 220 a to the inlet side of the automatic transmission through the vehicle delivery pipe.

As above, the amount of the working fluid (ATF) flowing through the tubes 211 can be reduced by a certain amount, when compared with the total amount of the working fluid supplied to the oil-cooler 200, because the certain amount of ATF bypasses the tubes 211 to directly flow from the sub-tank space 220 b to the sub-tank space 220 a through the aperture 251. As a result, the flow resistance for the working fluid can be reduced, while an appropriate heat exchange performance is maintained at the tubes 211.

Since the communication pipe 240 is arranged at the outer side of the built-up tubes 211, the heat exchange effect for the working fluid is small in the pipe 240. Accordingly, a temperature difference is generated between the pipe 240 and the tubes 211. A thermal deformation may be generated at the pipe 240 due to the temperature difference. However, such thermal deformation can be absorbed by the curved portion 241 of the pipe 240. As a result, stresses, which may be generated at connecting portions between the tubes 211 and the header tanks 220, 230, and between the pipe 240 and the header tanks 220, 230, can be reduced. A breakage of the connecting portions can be thus prevented.

Since the oil-cooler 200 having the pipe 240 and the separator 250 is integrally formed with the condenser 100, such that the first group of the tubes 211 and the second group of the tubes 111 are continuously built-up, the size of the heat exchanger 10 can be made smaller in a vehicle longitudinal direction. This enables an easier mounting of the heat exchanger 10 to the vehicle. Thus, the duplex type heat exchanger 10 can be obtained, wherein the different working fluid (the refrigerant and ATF) can be heat exchanged.

Since the tubes 111 for the condenser 100, the tubes for the oil-cooler 200, and the dummy tube 311 have the same specifications to each other, a sorting process is not necessary during an assembling process for the heat exchanger. As a result, a productivity for the core portions 110 and 210 can be increased. Namely, the core portions 110 and 120 can be assembled by simply building up the tubes of one type. Furthermore, since the fins 112 and 212 as well as the side plates 113 and 213 respectively have the same specifications, the productivity is further increased. In addition, forces for inserting the tubes into the tube holes provided in the header tanks as well as fitting forces between the tubes and tube holes of the header tanks can be uniformed due to the same specifications of the tubes 111 and 211, and thereby an assembling process can be easier.

Since the inlet and outlet pipes 261 and 262 are provided to the same header tank 220 on the right hand side, connecting portions of the vehicle delivery pipes can be located closer to each other, and a process for connecting the inlet and outlet pipes 261 and 262 with the vehicle delivery pipes can be made easier.

Since the dummy tube 311 is provided between the core portion 110 of the condenser 100 and the core portion 210 of the oil-cooler 200, the dummy tube 311 operates as an insulating member between the working fluids (the refrigerant and ATF) having different temperatures. Accordingly, the heat transfer between the condenser 100 and the oil-cooler 200 can be prevented, and heat affection to each other can be eliminated.

(Second Embodiment)

A second embodiment of the present invention is shown in FIG. 3. The second embodiment differs from the first embodiment in the position of the inlet pipe 261.

The inlet pipe 261 is provided to the header tank 230 on the left hand side, so that the inlet pipe 261 is fluidically connected to the sub-tank space 230 a. The outlet pipe 261 is provided to the header tank 220, as in the same manner to the first embodiment.

According to the second embodiment, the working fluid flows into the sub-tank space 230 c of the header tank 230 and then flows to the tank spaces 220 a and 220 b of the header tank 220 through the pipe 240 and tubes 211 in the same direction. The flow amount of the working fluid flowing through the pipe 240 is restricted to a certain amount by the aperture 251 provided at the separator 250. As above, the amount of the working fluid (ATF) flowing through the tubes 211 can be reduced by the certain amount, when compared with the total amount of the working fluid supplied to the oil-cooler 200, as in the same manner to the first embodiment. As a result, the flow resistance for the working fluid can be reduced, while an appropriate heat exchange performance is maintained at the tubes 211.

(Third Embodiment)

A third embodiment of the present invention is shown in FIG. 4. The third embodiment differs from the second embodiment in the position of the separator 250.

Namely, the separator 250 is provided in the header tank 230 on the left hand side at such a position between the pipe 240 and the uppermost tube 211.

According to the oil-cooler 200 of this embodiment, the working fluid (ATF) flows into a sub-tank space 230 a of the header tank 230 on the left hand side, and then flows to a sub-tank space 220 c of the header tank 220 on the right hand side through the tubes 211. A certain amount of the working fluid flows from the sub-tank space 230 a to a sub-tank space 230 b through the aperture 251 provided at the separator 250, and then flows to the sub-tank space 220 c through the pipe 240. As above, the amount of the working fluid (ATF) flowing through the tubes 211 can be reduced by the certain amount, when compared with the total amount of the working fluid supplied to the oil-cooler 200, as in the same manner to the second embodiment. As a result, the flow resistance for the working fluid can be reduced, while an appropriate heat exchange performance is maintained at the tubes 211.

(Fourth Embodiment)

A fourth embodiment of the present invention is shown in FIG. 5. The fourth embodiment differs from the first embodiment in the positions of the inlet and outlet pipes 261 and 262, namely the positions of the pipes 261 and 262 are counter changed.

In this embodiment, the working fluid flows into the sub-tank space 220 a of the header tank 220 on the right hand side through the inlet pipe 261. A major portion of the working fluid (ATF) flows from the sub-tank space 220 a to the sub-tank space 230 c of the header tank 230 on the left hand side through the tubes 211, and then flows through the pipe 240 into the sub-tank space 220 b of the header tank 220 on the right hand side, in a flow patter of a letter U, as indicated by a dotted line. The working fluid then flows out through the outlet pipe 262.

A certain portion (e.g. 20%) of the working fluid (ATF) in the sub-tank space 220 a directly flows into the upper sub-tank space 220 b through the aperture 251 of the separator 250, and then flows out from the sub-tank space 220 b through the outlet pipe 262.

Like the first embodiment, the amount of the working fluid (ATF) flowing through the tubes 211 can be reduced by a certain amount, when compared with the total amount of the working fluid supplied to the oil-cooler 200, by the separator 250 and the aperture 251. As a result, the flow resistance for the working fluid can be reduced, while an appropriate heat exchange performance is maintained at the tubes 211.

(Fifth Embodiment)

A fifth embodiment of the present invention is shown in FIG. 6. The fifth embodiment differs from the fourth embodiment in the positions of the condenser 100 and the oil-cooler 200.

The vertical positions of the condenser 100 and the oil-cooler 200 are counter changed, so that the oil-cooler 200 is arranged at a lower side of the condenser 100. This embodiment is preferable when the connecting portions of the vehicle delivery pipes are located at a lower portion of the engine compartment.

The oil-cooler 200 is vertically turned over from the position shown in FIG. 5 (the fourth embodiment). The super cooling portion 110B of the core portion 110 is arranged above the condensing portion 110A. A suction pipe 145 is arranged in the modulator 140, so that the condensing portion 110A is fluidically communicated with the super cooling portion 110B through the suction pipe 145.

According to the modification shown in FIG. 6, the same effect to the fourth embodiment can be obtained. As above, the position of the oil-cooler 200 can be changed depending on the locations of the vehicle pipe arrangement.

(Other Embodiments)

In the above embodiments, the duplex type heat exchanger 10 is explained, wherein the oil-cooler 200 is integrally formed with the condenser 100. In view of the feature that the flow resistance for the working fluid (ATF) can be reduced by the pipe 240 and the separator 250 (the aperture 251 as the bypass flow path), the present invention can be applied to the oil-cooler 200, even when the oil-cooler is separately formed from the condenser 100. The present invention can be also applied to other types of heat exchangers, such as a radiator, an inter-cooler, an oil-cooler for engine oil, or the like, other than the oil-cooler for the automatic transmission. The present invention can be further applied to heat exchangers to be used for the other purposes than the vehicles.

The curved portion 241 is not necessarily provided to the pipe 240, depending on the generation of the thermal deformation at the pipe 240. The pipe 240 may be formed as a straight form (without the curved portion 241), in the case that any problem may not be caused by the thermal deformation.

The sub-tank spaces 220 a and 220 b may not be necessarily communicated through the aperture 251. A slit having a certain opening area may be formed in the separator 250, so as to communicate the sub-tank spaces 220 a and 220 b with each other.

The second group of the tubes 111 may not be identical to the first group of the tubes 211. The tubes 111, which have different specifications from that of the tubes 211, may be used for obtaining maximum heat exchanging efficiencies at the respective core portions 110 and 210 for the condenser 100 and the oil-cooler 200.

The size and other specifications for the dummy tube 311 may not be the same to the tubes 111 or 211. The size and other specifications for the dummy tube 311 may be selected in consideration of the thermal affection between the heat exchangers (the condenser 100 and the oil-cooler 200). 

1. A heat exchanger comprising: a pair of first and second header tanks; an inlet pipe and an outlet pipe provided to one of the header tanks, the inlet and outlet pipes being connected to a heat generating device through delivery pipes so that working fluid is supplied from the heat generating device to the header tank to which the inlet and outlet pipes are provided and the working fluid returns to the heat generating device from the same header tank; a first group of multiple built-up tubes, both longitudinal ends of which are respectively connected to the header tanks, so that the working fluid flows from one of the header tanks to the other header tank through the multiple built-up tubes; a communication pipe connected between the header tanks so that tank spaces formed in the respective header tanks are fluidically communicated with each other through the communication pipe, the communication pipe being arranged at an outer side of the built-up tubes in a direction of building-up the tubes, the communication pipe having a flow path sectional area almost equal to that of the delivery pipes; a separator provided in the header tank to which the inlet and outlet pipes are provided, for dividing the tank space formed by the header tank into first and second sub-tank spaces, so that the first sub-tank space is communicated with the tubes and the second sub-tank space is communicated with the communication pipe; and a bypass flow path having a certain flow resistance and formed in the separator for communicating the first and second sub-tank spaces with each other, wherein the inlet pipe is fluidically connected to one of the sub-tank spaces, whereas the outlet pipe is fluidically connected to the other sub-tank space, so that a certain amount of the working fluid directly flows from the sub-tank space connected with the inlet pipe to the other sub-tank space connected with the outlet pipe through the bypass flow path, and the remaining amount of the working fluid flows from the sub-tank space connected with the inlet pipe to the other sub-tank space connected with the outlet pipe through the communication pipe and the multiple tubes.
 2. A heat exchanger according to claim 1, wherein a curved portion is provided at a middle portion of the communication pipe for absorbing thermal deformation in a longitudinal direction of the communication pipe.
 3. A heat exchanger according to claim 1, further comprising: another heat exchanger which includes; and another pair of third and fourth header tanks; a second group of multiple built-up tubes, both longitudinal ends of which are respectively connected to the other pair of header tanks, so that another working fluid flows from one of the third and fourth header tanks to the other of the third and fourth header tanks through the second group of the multiple built-up tubes, wherein the multiple tubes of the second group are continuously built-up in the same direction to that of the multiple tubes of the first group, and wherein the third and fourth header tanks are integrally formed with the respective first and second header tanks.
 4. A heat exchanger according to claim 3, wherein the multiple tubes of the second group have the same specifications to that of the multiple tubes of the first group.
 5. A heat exchanger according to claim 3, wherein a dummy tube is disposed between the multiple tubes of the first group and the multiple tubes of the second group, wherein the dummy tube is filled with air and no working fluid flows through the dummy tube.
 6. A heat exchanger according to claim 5, wherein the dummy tube has the same specifications to that of the multiple tubes of the first and second groups.
 7. A heat exchanger according to claim 3, wherein the heat exchanger is an oil-cooler for cooling the working fluid of an automatic transmission for a vehicle, and the other heat exchanger is a condenser for cooling refrigerant of an air conditioning apparatus for the vehicle.
 8. A heat exchanger comprising: a pair of first and second header tanks; an inlet pipe provided to the second header tank; an outlet pipe provided to the first header tanks, the inlet and outlet pipes being connected to a heat generating device through delivery pipes so that working fluid is supplied from the heat generating device to the second header tank and the working fluid returns to the heat generating device from the first header tank; a first group of multiple built-up tubes, both longitudinal ends of which are respectively connected to the header tanks, so that the working fluid flows from the second header tank to the first header tank through the multiple built-up tubes; a communication pipe connected between the header tanks so that tank spaces formed in the respective header tanks are fluidically communicated with each other through the communication pipe, the communication pipe being arranged at an outer side of the built-up tubes in a direction of building-up the tubes , the communication pipe having a flow path sectional area almost equal to that of the delivery pipes; a separator provided in the first header tank, for dividing the tank space formed by the first header tank into first and second sub-tank spaces, so that the first sub-tank space is communicated with the tubes and the second sub-tank space is communicated with the communication pipe; and a bypass flow path having a certain flow resistance and formed in the separator for communicating the first and second sub-tank spaces with each other, wherein a certain amount of the working fluid flows from the tank space formed by the second header tank to the second sub-tank space of the first header tank through the communication pipe, whereas the remaining amount of the working fluid flows from the tank space formed by the second header tank to the first sub-tank space of the first header tank through the multiple tubes, and wherein the working fluid flows from the second sub-tank space to the first sub-tank space though the bypass flow path and flows out of the first sub-tank space through the outlet pipe.
 9. A heat exchanger comprising: a pair of first and second header tanks; an inlet pipe provided to the second header tank; an outlet pipe provided to the first header tanks, the inlet and outlet pipes being connected to a heat generating device through delivery pipes so that working fluid is supplied from the heat generating device to the second header tank and the working fluid returns to the heat generating device from the first header tank; a first group of multiple built-up tubes, both longitudinal ends of which are respectively connected to the header tanks, so that the working fluid flows from the second header tank to the first header tank through the multiple built-up tubes; a communication pipe connected between the header tanks so that tank spaces formed in the respective header tanks are fluidically communicated with each other through the communication pipe, the communication pipe being arranged at an outer side of the built-up tubes in a direction of building-up the tubes, the communication pipe having a flow path sectional area almost equal to that of the delivery pipes; a separator provided in the second header tank, for dividing the tank space formed by the second header tank into first and second sub-tank spaces, so that the first sub-tank space is communicated with the tubes and the second sub-tank space is communicated with the communication pipe; and a bypass flow path having a certain flow resistance and formed in the separator for communicating the first and second sub-tank spaces with each other, wherein the inlet pipe is fluidically connected to the first sub-tank space, so that a certain amount of the working fluid directly flows from the first sub-tank space to the second sub-tank space through the bypass flow path, and then to the tank space formed by the first header tank through the communication pipe, and wherein the remaining amount of the working fluid flows from the first sub-tank space to the tank space formed by the first header tank through the multiple tubes.
 10. A duplex type heat exchanger for a vehicle comprising: a first heat exchanger having first and second header tanks and first multiple tubes, both longitudinal ends of the first multiple tubes being connected to the first and second header tanks so that tank spaces formed in the first and second header tanks are fluidically communicated with each other through the first multiple tubes; a second heat exchanger having third and fourth header tanks and second multiple tubes, both longitudinal ends of the first multiple tubes being connected to the third and fourth header tanks so that tank spaces formed in the third and fourth header tanks are fluidically communicated with each other through the second multiple tubes, wherein the third header tank is integrally formed with the first header tank and the fourth header tank is integrally formed with the second header tank; a communication pipe connected to the first and second header tanks, so that the tank spaces formed in the first and second header tanks are fluidically communicated with each other through the communication pipe; a separator provided in the first header tank for separating the tank space formed in the first header tank into first and second sub-tank spaces, so that each one end of the first multiple tubes is communicated with the first sub-tank space and one end of the communication pipe is communicated with the second sub-tank space; an inlet pipe provided to the first header tank to be fluidically communicated to the second sub-tank space, the inlet pipe being connected to an automotive parts device through a vehicle delivery pipe; an outlet pipe provided to the first header tank to be fluidically communicated to the first sub-tank space, the outlet pipe being connected to the automotive parts device through the vehicle delivery pipe; a bypass flow path formed in the separator, so that a portion of working fluid from the inlet pipe flows from the second sub-tank space to the tank space of the second header tank, whereas the remaining portion of the working fluid flows from the second sub-tank space to the first sub-tank space through the bypass flow path, wherein a flow path sectional area of the communication pipe is almost equal to that of the vehicle delivery pipe. 